Polymeric materials are used in countless applications including, but not limited to, fuel cell components, battery components, adhesives, gas barrier, and the like. Polymeric materials have been used in many fuel cell components such as the ion conducting membrane, the catalyst layers, the gas diffuse layers, adhesives that bind individual fuel cells in a stack, and gaskets.
In proton exchange membrane (PEM) type fuel cells, hydrogen is supplied to the anode as fuel and oxygen is supplied to the cathode as the oxidant. The oxygen can either be in pure form (O2) or air (a mixture of O2 and N2). PEM fuel cells typically have a membrane electrode assembly (“MEA”) in which a solid polymer membrane has an anode catalyst on one face, and a cathode catalyst on the opposite face. The anode and cathode layers of a typical PEM fuel cell are formed of porous conductive materials, such as woven graphite, graphitized sheets, or carbon paper to enable the fuel and oxidant to disperse over the surface of the membrane facing the fuel- and oxidant-supply electrodes, respectively. Each electrode has finely divided catalyst particles (for example, platinum particles) supported on carbon particles to promote oxidation of hydrogen at the anode and reduction of oxygen at the cathode. Protons flow from the anode through the ionically conductive polymer membrane to the cathode where they combine with oxygen to form water which is discharged from the cell. The MEA is sandwiched between a pair of porous gas diffusion layers (“GDL”). A sealing gasket is usual provided along the edges between the MEA and the GDL. The MEA/GDL assembly is sandwiched between a pair of non-porous, electrically conductive elements or plates with a sealing gasket along the edges. Typically, the sealing gaskets used in a fuel cell are polymeric with polyolefins being particularly useful. The plates function as current collectors for the anode and the cathode, and contain appropriate channels and openings formed therein for distributing the fuel cell's gaseous reactants over the surface of respective anode and cathode catalysts. In order to produce electricity efficiently, the polymer electrolyte membrane of a PEM fuel cell must be thin, chemically stable, proton transmissive, non-electrically conductive and gas impermeable. In typical applications, fuel cells are provided in arrays of many individual fuel cell stacks in order to provide high levels of electrical power.
Ziegler-Natta catalysts are a class of catalysts that have been utilized for making poly(α-olefins). Although these catalysts work reasonably well for forming non-fluorinated polyolefins, these catalysts have not been successfully used for forming perfluorinated polymers.
Accordingly, there is a need for improved methods for forming fuel cell membranes, diffusion media, fuel cell electrodes and battery separators.